Is this ad interesting enough?
In my school we have this student coaching, where students who are the best in certain subjects can teach it to other student. Usually the fees are around 20-40$ per hour. And you can coach the students in need of help whenever you don't have a class at school. I plan on coaching math and biology.
Here goes nothing :
"Math and Biology Coaching
Need help in math and biology? I could help out :) My time is flexible after 3pm. My fee is 10$/45min. Interested? You can reach me at (EMAIL) or SMS me at (NUMBER). "
Instead of repeating the same concept:
Math and Biology Coaching
Need help in math and biology
You might mention the goal: "up your exam scores", "get homework done quicker"
A different ad each week could mention the current curriculum topic that trips everyone up.